Cadillac Seville / Cadillac Eldorado Forum Discussion, Interior swap, What modules/parts need to swapped from my car? in Past Cadillac Vehicle Discussion; Car has been done for a couple of days. Been either too busy or too lazy to type a long ...

Car has been done for a couple of days. Been either too busy or too lazy to type a long post on the sound deadening process and post pics, but I'll get to it.

I like the black interior SOOO much better. Not only does it go with the crimson and black top better, IMO, it's just a better color to begin with. I like beige interiors, but I'm not a fan of Shale. It looks watered down or faded to me for some reason. The black doesn't make the interior feel any smaller like I thought it might, it just looks sleek. The car looks better from the outside as well, the tint looks much darker (I have 35% all around, you could almost mistake it for 20% now).

Also very happy with the sound proofing. It took just over 40 hours (a few hours a day, I didn't do any marathon runs, lol), and cost just over $500 for all materials. The car is noticeably quieter (not that it wasn't quiet to begin with), the faster you go, the bigger the difference from stock. 80 MPH is almost eerie (other than some tire noise from old Goodyears). Tire slap over expansion joints and small bumps is all but nonexistent. Nearby cars are silent, other than large trucks with all terrain tires. All that's audible is drivetrain noise, and the impact of potholes and larger bumps. The sound system sounds better, tighter, and there are zero vibrations or buzzes from anything, even at max volume with bass heavy music. Unexpected side effect, the window motors are almost inaudible now. The first time I went to roll them up, I was looking forward, and thought they weren't working.

I've been putting this off, because I'm imagining it's going to be a huge post, but maybe it just seems that way because of the amount of work it took to do.

When most people think sound deadening, they think a layer, or multiple layers of Dynamat covering every square inch of the interior. Well, here's an idea of the extent of the amount of Dynamat in my car:

You're probably thinking the Seville's driven me completely broke, and I bought 2 sheets of Dynamat, and scattered it throughout the car. Not exactly.

Dynamat is a CLD (Constrained Layer Damper). It is NOT a sound deadener, a sound barrier, or a sound absorber. So what does it do? It stops panel resonance (essentially stops body panels from vibrating, so that they don't act like big speakers) by converting vibrations, to heat. A CLD does not have to cover the entire surface to stop it from resonating, it actually only has to cover ~25% to do its job. On top of that, it really only needs to be applied to flat surfaces, as contoured sections of the body panels are strong, and don't really resonate anyway.

Another thing that leads to layers and layers of CLD to be used, is that it works by increasing the weight of the panels. In reality, the amount of weight that would have to be added to get the resonance out of the range of human hearing, is insane (for starters, think doors that weigh hundreds of pounds...).

The process is pretty simple. Knock on different areas of the body panels, listen for the areas that "ring", and apply CLD to ~25% of that area. The car actually has CLD in it from the factory, a square in each foot well, and 3 across the area behind the rear seat back (and also a piece inside each front door).

So now that the panels aren't making a y noise of their own, what is used to actually BLOCK sound (road noise, traffic noise, exhaust noise...) from entering the car? A product called MLV (Mass Loaded Vinyl). A limp, very dense, VERY heavy vinyl all perfect qualities for reflecting/stopping sound waves. This material is used in building construction in various thicknesses. For automotive purposes, it's 1/8" thick, and just about 1 pound per square foot. It's very surprising, and almost comical to hold, as you're just not expecting fairly small pieces of such a thin material to weigh much of anything.

^^That^^ is a 56 inch wide, 108 SQ/FT roll of MLV. It weighs 106 pounds. The point, is to have an unbroken layer of it covering as much of the body as possible, up to window level. Obviously, it can't be a 100% solid layer in a car, wiring and bolts have to be passed through, various things have to be mounted directly to the sheet metal, and some shapes are just too complicated to cover with a material that DOES NOT STRETCH OR COMPRESS AT ALL. MLV will conform to simple bends, but only in one direction at a time, so compound curves are impossible. This means that everywhere there's a compound curve, it needs to be cut, and a seem has to be made, sometimes using a smaller piece/strip to close any gaps that it was necessary to make.

In the end, you end up with an almost complete layer of MLV from the lower part of the firewall, to the top of the rear seat back (and also on the B pillars and doors, but we'll get to that later).

Here are some pictures, just in the order I took them. In them, you can see where pieces were glued together (using vinyl specific contact adhesive), how some complex shapes were covered, and where Velcro (with vinyl specific adhesive) was used to hold the separate pieces in place (overlapped by ~1 1/2" to maintain a solid layer).

There is an access flap for the battery and fuse panel:

That is the largest (and heaviest) single piece in the car. It starts at the top of the seat back, and goes all the way down to the front of the seat bottom. Here it is out of the car:

If you look close, some of the lower edge is cut very jagged. That's because it butts up against seam sealer that is applied thick and messy.

You'll also notice the light grey foam attached to the backside of the vinyl. I'll explain that when I go over the process of sound deadening the doors. I've been getting pictures together and typing for ~an hour, and I need a break.

I keep forgetting I still haven't swapped in the fuzzy "weatherstripping" around the doors. I kept the shale ones on while I was taking things in and out of the car, so I wouldn't damage the black ones. I went to do it today, took the drivers door one off, and found this:

It's rust, but the metal is solid as a rock. Went to the body shop, the manager I always deal with says it's not from water (it's on a vertical/upside down surface ), but from a manufacturing defect or damage (contamination on bare metal, a scratch in the anticorrosive coating under the paint...) Not expensive to fix, he's going to media blast, treat, and paint the area... but the stupid headliner has to come out again :banghead.

...Sooo, the pillar trim is off in the pictures. Otherwise, I gave it a quick vacuum, and here you are:

Still disappointed that someone took the nearly perfect seats out of the car that I got the original interior out if. These will do until I have the custom upholstery done, probably in the spring summer. But for now, just a stock, black interior.

I'll have something more exciting to post in the next several weeks though.....

Black isn't my first choice most of the time either, I like beige/brown, but shale was just too light for me, and just didn't go with the exterior at all IMHO. I'll have to take one from the outside with the windows open.